Endocarditis

Endocarditis Basics - Inner Lining Invasion

• Inflammation of the endocardium (inner lining of heart chambers & valves), primarily affecting heart valves.
• Etiology:
  • Infective: Bacterial (most common), fungal.
  • Non-infective: e.g., Non-bacterial Thrombotic Endocarditis (NBTE).
• Pathogenesis: Endothelial injury → platelet-fibrin nidus (may start as NBTE) → microbial adherence & colonization → vegetation formation.
  • Vegetations: Core lesions; consist of microorganisms, fibrin, platelets, inflammatory cells.
• Valve Involvement Order (most to least common): Mitral > Aortic > Tricuspid > Pulmonic (📌 My Awesome Tall Partner).
  • IV drug users (IVDU): Tricuspid valve frequently affected (often S. aureus).
• Key Types:
  • Acute Bacterial Endocarditis (ABE): Rapid, destructive; high-virulence organisms (e.g., S. aureus); often affects normal valves.
  • Subacute Bacterial Endocarditis (SBE): Insidious onset; lower-virulence organisms (e.g., Viridans streptococci); typically on pre-damaged valves.
  • Prosthetic Valve Endocarditis (PVE).

⭐ Non-bacterial thrombotic endocarditis (NBTE) is often associated with malignancy or hypercoagulable states, presenting as small, sterile vegetations on cardiac valves. 侵

Etiology & Pathogenesis - Microbial Mayhem

Key Microbial Culprits:

• Bacteria (Dominant):
  • Staphylococcus aureus: #1 in acute IE & IVDU (tricuspid focus).

    ⭐ Staphylococcus aureus is the most common cause of acute Infective Endocarditis (IE) and IE in IV drug users, often affecting the tricuspid valve.

  • Viridans streptococci: Subacute IE, damaged native valves (post-dental).
  • Streptococcus gallolyticus (bovis): Colorectal cancer link (colonoscopy needed).
  • Enterococci: Nosocomial, elderly, post-GU procedures.
  • 📌 HACEK: Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella (Gram-negative, fastidious, large vegetations, often culture-negative).
• Fungi (Candida, Aspergillus): Immunocompromised, PVE, IVDU.
• Non-infective (NBTE): Marantic (cancer), Libman-Sacks (SLE).

Pathogenesis Unveiled:

Clinical Picture - Systemic Storm Signs

• General: Fever (often low-grade), chills, malaise, anorexia, weight loss, night sweats.
• Cardiac:
  • New/changed heart murmur (>85% cases).
  • Heart failure signs (dyspnea, edema) due to valve damage.
• Peripheral Manifestations (Embolic & Immunologic):
  • 📌 Mnemonic: FROM JANE
    • Fever
    • Roth spots (retinal hemorrhages)
    • Osler nodes (painful nodules; fingers/toes)
    • Murmur (new/changed)
    • Janeway lesions (painless macules; palms/soles)
    • Anemia
    • Nail-bed hemorrhages (splinter hemorrhages)
    • Emboli
  • Splenomegaly
  • Clubbing (late)
  • Glomerulonephritis

  ⭐ Osler's nodes are painful, violaceous nodules typically on fingers/toes (immunological complex deposition), while Janeway lesions are painless, erythematous macules on palms/soles (septic microemboli).

Diagnosis & Management - Unmasking & Mending

⭐ The Modified Duke Criteria require 2 Major, OR 1 Major + 3 Minor, OR 5 Minor criteria for definite Infective Endocarditis.

• Diagnosis:
  • Blood Cultures: 3 sets, 1 hr apart, pre-antibiotics.
  • Echocardiography: TTE first; TEE if high suspicion/prosthetic valve/complications.
  • Modified Duke Criteria:
    • Major: Positive blood culture, Echo evidence (vegetation, abscess, new regurgitation).
    • Minor: Predisposition, Fever (>38°C), Vascular (Janeway), Immunologic (Osler, Roth spots), Non-major micro evidence.
• Management:
  • Empirical: Vancomycin + Gentamicin/Ceftriaxone.
  • Tailored: Culture-guided, 4-6 weeks IV.
  • Surgery: HF, uncontrolled infection, large vegetation (>10mm), emboli, fungal.

High‑Yield Points - ⚡ Biggest Takeaways

• Staph aureus is the most common cause of IE, especially in IVDU (tricuspid). Strep viridans for subacute native valve IE.
• Culture-negative IE: Suspect Coxiella, Bartonella, HACEK, or prior antibiotics.
• Duke criteria (blood cultures, echo: vegetations) are key for diagnosis.
• Peripheral stigmata: Janeway lesions (non-tender), Osler's nodes (tender), Roth spots.
• Libman-Sacks endocarditis (sterile) is linked to SLE.
• Early Prosthetic Valve Endocarditis (PVE): Staph epidermidis is a common cause.